Prior to the present invention, devices for trimming a margin from a film along the length thereof to reduce the width thereof thereby, consisted of opposing cutting wheels of which each had a cutting edge with their respective cutting edges contacting each other with the wheels being mounted in overlapping relationships such that a tape or film fed along a circumscribing wheel outer-surface of one of the wheel became pinched and severed at the point of wheels-overlapping and cutting by the respective blades simultaneously, to sever the marginal width of film or tape carried by the film-mounting one of the wheels. Such severing when the apparatus was new worked well, but in order to operate neatly and efficiently, the opposing wheels and thereby the opposing cutting edges were required to be pressed against one-another firmly in order to cut at the pinch point, and such constant and necessary pressure resulted in a wearing of the respective cutting edges of the wheels as well as a wearing of the bearing mountings thereof to result in a rapid deterioration of effective and accurate cutting. Such required therefor frequent replacement and maintenance of parts. Also, accuracy or precision in trimming an exact and continually consistant predetermined width of margin was lacking with the prior devices.